This invention relates to methods of manufacturing packaging containers having a hollow body which is adapted to contain the commodity.
The known method of manufacturing packaging containers equipped with valves is described, as for example, in the French Pat. No. 1300753. This method of producing a packaging bag comprises a step of connecting two superimposed coextensive members formed of a plastic foil by welding the edges of two members in connection with a channel formed therebetween. In order to seal this channel a moisture fluid is applied onto the limited area of the boundaries of the foil surfaces before the welding of the foil members. This flowing fluid does not provide a uniform layer on the surface of the members and prevents the formation of channels of predetermined dimension sizes and smooth surfaces.